Non-invasive techniques for diagnosis and determination of status of humans or animals are increasingly winning ground since these pose low risk for the patient and are usually low cost as compared to invasive techniques. Especially considering the brain, non-invasive techniques may provide convenient and safe ways of determination of the brain status. However, the common techniques for this are not able to determine all types of parameters of need, which means that there are blind spots where invasive techniques are still used.
Furthermore, some non-invasive techniques provide solutions where the patient is still put in risk of danger, for instance where x-rays are used the patient will be subjected to a dose of radiation potentially harmful and it can in many cases not be used for continuously or semi-continuously (i.e. intermittently) monitor the status of parameters in the brain (or in any other part of the body).
Some of the known non-invasive techniques will give some information but there is a need for getting more information about the monitored part.
Medical instrumentation is quite expensive due to their complex nature and can often only be used for one type of ailment.
One application of the invention deals with the task of detecting increased intracranial pressure (ICP) by means of electromagnetic radiation in the microwave region. The standard method to monitor brain swelling resulting from head injury is by measuring the intracranial pressure. A pressure probe is inserted through a burr hole in the skull bone and the mean pressure is registered on an hourly basis. If the pressure raises several treatments is activated where the most extreme one is surgical removal of parts of the skull bone (craniectomy) to allow brain swelling to occur without the dangerous pressure increase. If incidents of severe brain swelling could be better predicted the treatment could be more selective and provide an overall better result in the treatment. At present monitoring of the semi-static intracranial pressure (ICP) is the main basis for the treatment of brain swelling of different etiologies. As done today, ICP is measured at one point intracranially. The probe cannot detect pressure gradients and cannot say anything about the cause of a possible increase of the ICP. There can be development of substantial contusions and even hematomas of potentially life-threatening magnitude, before the measured ICP increases significantly. A special case when this risk is high is when there is a need for continuous deviation of cerebrospinal fluid. Today, the monitored data cannot give enough information to reliably predict all episodes of dangerously high ICP. This is a common clinical experience. Hence, there is a clinical need for new sensor systems.
With today's technique of making a hole in the skull to insert a pressure probe is a significant risk associated that the patient will develop an infection in the vicinity of the hole. The largest benefit with the present invention is that it can be made completely non-invasive and thus all the risks associated with ICP measurements today can be eliminated.
Another area of application for the current invention is in diagnosing stroke patients by means of a sensor system that can be used in an ambulance for assessments of patient with suspected stroke. Internationally ambulance service paramedics have been trained to use a stroke recognition tool to speed up transfer and assessment of patients with suspected stroke. This facilitates the time critical intervention of thrombolysis which has been shown to improve the outcome from ischaemic stroke if given in time. The proposed system develops this one step further by providing additional information to be able to distinguish between ischaemic and haemorrhagic stroke.
Microwave techniques can provide non-invasive, easy access, to the human brain at a relatively low cost providing a large amount of multi frequency scattering data that can be used to analyze the continues developments of the dielectric and geometric properties of the human brain. Developments of the methods in the project may result in an imaging modality for traumatic brain injury patients allowing for a continuous bedside brain imaging system. It would also be possible to extend the method to include monitoring of other parts of the body, e.g. the abdomen in case of suspected internal bleeding. In that case the antenna system has to be suitably designed but the analysis could be done with the same equipment as for the brain monitoring.